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Biomolecules. 2015 Feb 9;5(1):95-112. doi: 10.3390/biom5010095.

Redox-regulated pathway of tyrosine phosphorylation underlies NF-κB induction by an atypical pathway independent of the 26S proteasome.

Author information

1
Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. cullensarahjane@gmail.com.
2
Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. SPonnappan@uams.edu.
3
Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. UPonnappan@uams.edu.
4
Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. UPonnappan@uams.edu.

Abstract

Alternative redox stimuli such as pervanadate or hypoxia/reoxygenation, induce transcription factor NF-κB by phospho-tyrosine-dependent and proteasome-independent mechanisms. While considerable attention has been paid to the absence of proteasomal regulation of tyrosine phosphorylated IκBα, there is a paucity of information regarding proteasomal regulation of signaling events distinct from tyrosine phosphorylation of IκBα. To delineate roles for the ubiquitin-proteasome pathway in the phospho-tyrosine dependent mechanism of NF-κB induction, we employed the proteasome inhibitor, Aclacinomycin, and the phosphotyrosine phosphatase inhibitor, pervanadate (PV). Results from these studies demonstrate that phospho-IκBα (Tyr-42) is not subject to proteasomal degradation in a murine stromal epithelial cell line, confirming results previously reported. Correspondingly, proteasome inhibition had no discernable effect on the key signaling intermediaries, Src and ERK1/2, involved in the phospho-tyrosine mechanisms regulating PV-mediated activation of NF-κB. Consistent with previous reports, a significant redox imbalance leading to the activation of tyrosine kinases, as occurs with pervanadate, is required for the induction of NF-κB. Strikingly, our studies demonstrate that proteasome inhibition can potentiate oxidative stress associated with PV-stimulation without impacting kinase activation, however, other cellular implications for this increase in intracellular oxidation remain to be fully delineated.

PMID:
25671697
PMCID:
PMC4384113
DOI:
10.3390/biom5010095
[Indexed for MEDLINE]
Free PMC Article

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